Method for manufacturing liquid crystalline resin

Abstract

To provide a method for producing a liquid crystalline resin which can produce a liquid crystalline resin by suppressing foreign matter contamination with high yields.SOLUTION: There is provided a method for producing a liquid crystalline resin, which comprises subjecting a raw material monomer containing one or more selected from the group consisting of an aromatic hydroxycarboxylic acid and a polymerizable derivative thereof to melt polycondensation reaction in a reaction vessel, wherein in performing the melt polycondensation reaction, the melting point of the liquid crystalline resin is defined as Tm2, the raw material monomer is subjected to a melt polycondensation reaction at a polymerization temperature within the range of Tm2 to (Tm2+30)°C and the temperature of an area of the reaction vessel in contact with a space above the reaction liquid surface during the melt polycondensation reaction is adjusted within the range of (Tm2-100) to (Tm2-5)°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing liquid crystalline resin. [Background technology]

[0002] Liquid crystal resins are widely used as high-performance engineering plastics because they possess a good balance of excellent mechanical strength, heat resistance, chemical resistance, and electrical properties, as well as excellent dimensional stability. A known method for manufacturing liquid crystal resins involves acylation of the raw material monomers as needed, followed by melt polycondensation. When manufactured by batch-type continuous polymerization, sublimated monomers adhering to the polymerization vessel undergo thermal history, resulting in foreign matter with a higher melting point than the normal polymer. This foreign matter may be mixed into the polymer when the polymer is discharged from the polymerization vessel after polymerization is complete. Patent Document 1 describes maintaining the temperature of the reactor portion in contact with the reaction space at 150-300°C during the polycondensation reaction when producing aromatic polymers in a batch process. Patent Document 2 describes performing polycondensation while controlling the temperature of the reaction vessel liquid surface and the portion located near the reaction liquid surface above it within the range of 70-200°C. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2003 / 062299 [Patent Document 2] Japanese Patent Application Publication No. 10-7781 [Overview of the project] [Problems that the invention aims to solve]

[0004] By lowering the temperature of the region in contact with the space above the reaction liquid surface in the polymerization vessel, it is possible to prevent the contamination of the polymer with foreign matter. On the other hand, lowering the temperature of the region in contact with the space above the reaction liquid surface tends to reduce the yield of the resulting liquid crystalline resin, even if the final polymerization temperature is set to an optimal temperature. In other words, there is a trade-off between suppressing foreign matter contamination and improving yield.

[0005] The object of this invention is to provide a method for producing liquid crystalline resin that can suppress the inclusion of foreign matter and produce liquid crystalline resin in good yield. [Means for solving the problem]

[0006] [1] A method for producing liquid crystal resin, The process involves melt polycondensation of a starting monomer containing one or more selected from the group consisting of aromatic hydroxycarboxylic acids and their polymerizable derivatives in a reaction vessel. When a melt polycondensation reaction is performed, and the melting point of the liquid crystalline resin is Tm2, A method for producing a liquid crystalline resin, comprising: melting and polycondensing raw material monomers at a final polymerization temperature in the range of Tm2 to (Tm2 + 30)°C; and maintaining the temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melting and polycondensing reaction within the range of (Tm2 - 100) to (Tm2 - 5)°C. [2] The raw material monomers are One or more selected from the group consisting of aromatic or alicyclic dicarboxylic acids and their polymerizable derivatives, One or more selected from the group consisting of aromatic or alicyclic diols, aromatic or alicyclic hydroxyamines, aromatic or alicyclic diamines, and polymerizable derivatives thereof, A method for producing a liquid crystal resin according to [1], further comprising: [3] A method for producing a liquid crystalline resin according to [1] or [2], comprising keeping the temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melt polycondensation reaction within the range of (Tm2-40) to (Tm2-5)°C. [4] A method for producing a liquid crystalline resin according to any one of [1] to [3], further comprising acylation of the raw material monomer with a fatty acid anhydride before melt polycondensation reaction. [5] A method for producing a liquid crystalline resin according to any one of [1] to [4], wherein the reaction vessel includes a stirrer, a reflux column, a raw material monomer supply port, a reduced pressure line and an outlet line. [6] The melt polycondensation reaction includes carrying out the melt polycondensation reaction while distilling off the fatty acids, A method for producing a liquid crystalline resin according to any one of [1] to [5], wherein at least a portion of the distilled fatty acids is refluxed into a polymerization vessel. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for producing liquid crystalline resin that can suppress the inclusion of foreign matter and produce liquid crystalline resin in good yield. [Brief explanation of the drawing]

[0008] [Figure 1] This is an explanatory diagram showing an example of a polymerization apparatus that can be used in the method for producing liquid crystalline resin according to this embodiment. [Modes for carrying out the invention]

[0009] The following describes in detail one embodiment of the present invention, but the scope of the present invention is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the invention. Furthermore, if multiple upper and lower limits are described for a particular parameter, any combination of these upper and lower limits can be used to obtain a suitable numerical range. If a particular description given for one embodiment also applies to other embodiments, that description may be omitted in the other embodiments.

[0010] [Method for manufacturing liquid crystal resin] The method for producing a liquid crystalline resin according to this embodiment includes subjecting a raw material monomer, which comprises one or more selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof, to a melt polycondensation reaction in a reaction vessel.

[0011] In one embodiment, the method for producing the liquid crystalline resin may be a method for producing liquid crystalline polyester and / or liquid crystalline polyesteramide. In one embodiment, the method for producing the liquid crystalline resin may be a method for producing all aromatic polyester and / or all aromatic polyesteramide. In one embodiment, it is preferable that the obtained liquid crystalline resin contains one or more selected from the group consisting of all aromatic polyester and all aromatic polyesteramide.

[0012] (raw material monomers) The raw material monomer comprises one or more compounds selected from the group consisting of aromatic hydroxycarboxylic acids and their polymerizable derivatives. In this disclosure, "polymerizable derivative" means a compound in which part of the molecular structure has been changed and which can be polymerized by melt polymerization. Examples include acylated compounds obtained by acyling the phenolic hydroxyl group and / or amino group with an acyling agent, acid halides obtained by halogenating the carboxyl group with a halogenating agent, acid anhydrides, alkyl esters (with approximately 1 to 4 carbon atoms), etc.

[0013] The aromatic hydroxycarboxylic acids and their polymerizable derivatives are not particularly limited, and examples thereof include 4-hydroxybenzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA), 3-hydroxybenzoic acid, 6-hydroxy-3-naphthoic acid, 6-hydroxy-4-naphthoic acid, 4-hydroxy-4'-carboxydiphenyl ether, 2,6-dichloro-p-hydroxybenzoic acid, 2-chloro-p-hydroxybenzoic acid, 2,6-dimethyl-p-hydroxybenzoic acid, 2,6-difluoro-p-hydroxybenzoic acid, 4-hydroxy-4'-biphenylcarboxylic acid, vanillic acid, and the like. At least one compound selected from these can be used. Among them, from the viewpoint of easy availability, it is preferable to use at least one selected from 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid.

[0014] The raw material monomer preferably further satisfies the following (1) or (2). (1) containing at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and their polymerizable derivatives, or (2) containing at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and their polymerizable derivatives and at least one compound selected from the group consisting of aromatic or alicyclic diols, aromatic or alicyclic hydroxyamines, aromatic or alicyclic diamines, and their polymerizable derivatives.

[0015] When the raw material monomer contains an aromatic or alicyclic dicarboxylic acid and / or an aromatic or alicyclic diol, the sublimation product of the raw material monomer is likely to be generated and is likely to cause foreign matter contamination. According to the method for producing a liquid crystalline resin according to the present embodiment, even when the raw material monomer contains an aromatic or alicyclic dicarboxylic acid and / or an aromatic or alicyclic diol, it is possible to suppress the contamination of foreign matter and to produce a liquid crystalline resin with good yield.

[0016] In one embodiment, the raw material monomer may further include one or more selected from the group consisting of aromatic or alicyclic dicarboxylic acids and polymerizable derivatives thereof, and one or more selected from the group consisting of aromatic or alicyclic diols, aromatic or alicyclic hydroxyamines, aromatic or alicyclic diamines, and polymerizable derivatives thereof.

[0017] Aromatic dicarboxylic acids are not particularly limited and include, for example, terephthalic acid (TA), isophthalic acid (IA), 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and compounds represented by the following general formula (I). General formula (I): TIFF0007857161000001.tif21170(Y:-(CH2) n -(n=1~4) and -O(CH2) n It is a base selected from O-(n=1~4).

[0018] The alicyclic dicarboxylic acid is not particularly limited, and examples include 1,4-cyclohexanedicarboxylic acid and 1,3-cyclopentanedicarboxylic acid. The polymerizable derivative is not particularly limited, and examples include alkyl esters (with approximately 1 to 4 carbon atoms) and halides of the above compounds.

[0019] Aromatic diols are not particularly limited and include, for example, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl (BP), hydroquinone, resorcinol, compounds represented by the following general formula (II), and compounds represented by the following general formula (III).

[0020] General formula (II): TIFF0007857161000002.tif23170(X: A group selected from alkylene (C1~C4), alkylidene, -O-, -SO-, -SO2-, -S-, and -CO-.)

[0021] General formula (III): TIFF0007857161000003.tif24170

[0022] The alicyclic diol is not particularly limited, and examples include 1,4-cyclohexanedimethanol and 1,4-cyclohexanediol. The polymerizable derivative is not particularly limited, and examples include alkyl esters (with approximately 1 to 4 carbon atoms) and halides of the above compounds.

[0023] Aromatic hydroxyamines are not particularly limited and include, for example, 4-aminophenol, 3-aminophenol, and N-acetyl-p-aminophenol (APAP). Alicyclic hydroxyamines are not particularly limited and include, for example, 4-aminocyclohexanol and 3-aminocyclopentanol. Polymerizable derivatives are not particularly limited and include alkyl esters (approximately 1 to 4 carbon atoms) and halides of the above compounds.

[0024] Examples of aromatic diamines include 1,4-phenylenediamine. Examples of alicyclic diamines include 1,4-cyclohexanediamine and 1,3-cyclopentanediamine. Examples of polymerizable derivatives include alkyl esters (with approximately 1 to 4 carbon atoms) and halides of the above compounds.

[0025] Specific combinations of raw material monomers include, for example, (I)(a) comprising at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof (preferably consisting only of at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof); and, (II) comprising (a) at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof, (b) at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and polymerizable derivatives thereof, and (c) at least one compound selected from the group consisting of aromatic or alicyclic diols, aromatic hydroxyamines, aromatic diamines, and polymerizable derivatives thereof (preferably consisting only of compound (a), compound (b), and compound (c)); A combination can be selected from these. Furthermore, molecular weight adjusters may be used in combination with the above components as needed.

[0026] (Polycondensation reaction process) In the polycondensation reaction process, the raw material monomers are subjected to a melt polycondensation reaction (hereinafter also simply referred to as the "polycondensation reaction") in a reaction vessel.

[0027] In the method for producing the liquid crystalline resin according to this embodiment, the melt polycondensation reaction step is such that, when the melting point of the liquid crystalline resin is Tm2, The method is characterized by carrying out a melt polycondensation reaction of raw material monomers at a final polymerization temperature within the range of Tm2 to (Tm2 + 30)°C, and maintaining the temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melt polycondensation reaction within the range of (Tm2 - 100) to (Tm2 - 5)°C.

[0028] In a method for producing a liquid crystalline resin by melt polycondensation reaction of raw material monomers containing one or more selected from the group consisting of aromatic hydroxycarboxylic acids and their polymerizable derivatives, by setting the final polymerization temperature and the temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melt polycondensation reaction within the above range, it is possible to achieve both an effect of suppressing foreign matter contamination and an effect of improving yield.

[0029] If the final polymerization temperature is below Tm2 (°C), the yield of the resulting liquid crystalline resin decreases. If the final polymerization temperature exceeds (Tm2 + 30)°C, side reactions such as branching reactions are more likely to occur, which is undesirable.

[0030] If the temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melt polycondensation reaction is below (Tm2-100)°C, the yield of the resulting liquid crystalline resin will decrease, even if the final polymerization temperature is set to an appropriate temperature. If the temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melt polycondensation reaction exceeds (Tm2-5)°C, foreign matter is more likely to be mixed into the polymer.

[0031] "Melting point Tm2 of liquid crystalline resin" refers to the melting point Tm2 of the liquid crystalline resin obtained in the melt polycondensation process, as measured by a differential scanning calorimeter. The melting point Tm2 is determined by the method based on JIS K-7121 (1999). After measuring the peak temperature (melting point Tm1) of the endothermic peak observed when heating from room temperature at a heating rate of 20°C / min (1st RUN), the temperature is held at (melting point Tm1 + 40)°C for 2 minutes, then cooled to room temperature at a cooling rate of 20°C / min, and then heated again from room temperature at a heating rate of 20°C / min (2nd RUN). The peak temperature of the endothermic peak observed during the 2nd RUN is defined as the peak temperature of the endothermic peak observed during the 2nd RUN.

[0032] "Final polymerization temperature" refers to the final temperature reached by the reaction solution during a polycondensation reaction. The final polymerization temperature is the temperature indicated by the thermometer installed in the temperature control device of the reaction vessel. "Space above the reaction liquid level" refers to the space located above the reaction liquid level within the internal space of the reaction vessel where the melt polycondensation reaction takes place. In one embodiment, the space above the reaction liquid level may be a sealed space. In one embodiment, the space above the reaction liquid level may be the space surrounded by the sides of the reaction vessel, the top lid of the reaction vessel, and the reaction liquid level.

[0033] "The region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melt polycondensation reaction" includes the sides and top surface of the reaction vessel that are in contact with the space above the reaction liquid surface during the melt polycondensation reaction. In addition, if the reaction vessel is equipped with a top lid, reflux column, depressurization line, outflow line, etc., and these components are in contact with the space above the reaction liquid surface in the reaction space within the reaction vessel during the melt polycondensation reaction, then the region of these components may also be included. The temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melt polycondensation reaction shall be the temperature indicated by a thermometer provided by a temperature control device installed outside the region.

[0034] The final polymerization temperature of the polycondensation reaction is in the range of Tm2 to (Tm2 + 30)°C, preferably in the range of Tm2 to (Tm2 + 20)°C, more preferably in the range of (Tm2 + 5) to (Tm2 + 20)°C, and even more preferably in the range of (Tm2 + 5) to (Tm2 + 15)°C, where Tm2 is the melting point of the liquid crystalline resin.

[0035] During the melt polycondensation reaction, the temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface is in the range of (Tm2-100) to (Tm2-5)°C, preferably in the range of (Tm2-90) to (Tm2-8)°C, more preferably in the range of (Tm2-80) to (Tm2-9)°C, and even more preferably in the range of (Tm2-75) to (Tm2-10)°C, where Tm2 is the melting point of the liquid crystalline resin. In one embodiment, it is particularly preferable that the temperature of the region of the reaction vessel that is in contact with the space above the reaction liquid surface during the melt polycondensation reaction is within the range of (Tm2-40) to (Tm2-5)°C.

[0036] One method for adjusting the final polymerization temperature to be within the range of Tm2 to (Tm2 + 30)°C, and for adjusting the temperature of the components in the region of the reaction vessel that are in contact with the space above the reaction liquid surface during the melt polycondensation reaction to be within the range of (Tm2 - 100) to (Tm2 - 5)°C, is to install separate temperature control devices (heating or cooling means such as band heaters or jacket heaters) in the upper and lower parts of the reaction vessel and control the temperature separately.

[0037] In one embodiment, the lower part of the reaction vessel is heated with a band heater or jacket heater (first heating means) so that the reaction solution reaches the final polymerization temperature, and the upper part of the reaction vessel and / or components located above the reaction vessel, such as the top lid and reflux column, are heated or cooled with a band heater or jacket heater (second heating or cooling means).

[0038] A temperature control device (second heating or cooling means) for managing the temperature of the region in contact with the space above the reaction liquid surface during a melt polycondensation reaction is preferably a band heater, from the viewpoint of facilitating temperature control.

[0039] In polycondensation reactions, catalysts can be used to accelerate the reaction. Examples of catalysts include metal salt catalysts and organic compound catalysts, and it is preferable to use at least one catalyst selected from these. Examples of metal salt catalysts include potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, and antimony trioxide. Examples of organic compound catalysts include N-methylimidazole and 4-dimethylaminopyridine.

[0040] The amount of catalyst used is generally preferably 0.001 to 1% by mass, and more preferably 0.005 to 0.5% by mass, relative to the total amount of raw material monomers.

[0041] The polycondensation reaction is carried out by heating a starting monomer, which includes one or more selected from the group consisting of aromatic hydroxycarboxylic acids and their polymerizable derivatives, in a reaction vessel of a polymerization apparatus at an arbitrary heating rate until a predetermined final polymerization temperature is reached. Preferably, the pressure inside the reaction system is reduced (preferably 200 to 5 Torr, more preferably 50 to 5 Torr), and preferably while distilling off fatty acids such as acetic acid generated during the polycondensation reaction. Usually, stirring is started at the same time as the heating starts. The polymerization apparatus is preferably a batch-type polymerization apparatus so that polymerization can be carried out continuously.

[0042] The reaction vessel is preferably equipped with a stirring device, a temperature control device, and a pressure control device. Examples of temperature control devices include heating or cooling means such as a band heater or jacket heater and a thermometer for measuring the temperature. Examples of pressure control devices include a vacuum pump, an ejector, and a pressure gauge for measuring the pressure.

[0043] The reaction vessel preferably has a top lid. In this case, separate heating or cooling means may be provided on the outer surface of the top lid and the outer surface of the reaction vessel. The reaction vessel preferably has a raw material monomer supply port and / or polymer discharge port. The reaction vessel preferably has an inlet for an inert gas such as nitrogen.

[0044] In one embodiment, the reaction vessel preferably includes a stirrer, a reflux column, a raw material monomer supply port, a reduced pressure line, and an outlet line. The reduced pressure line and outlet line are lines used to reduce the pressure inside the reaction vessel and distill off fatty acids such as acetic acid that are generated during the polycondensation reaction. This allows the melt polycondensation reaction to be carried out while distilling off fatty acids such as acetic acid that are generated in the melt polycondensation reaction step. The reflux column is a line that refluxes at least a portion of the fatty acids removed by the above method back into the reaction vessel. By refluxing at least a portion of the removed fatty acids back into the reaction vessel, the contamination of the polymer with foreign matter can be further reduced.

[0045] In one embodiment, the melt polycondensation step includes carrying out the melt polycondensation reaction while distilling off the fatty acids generated by the melt polycondensation reaction, and may include refluxing at least a portion of the distilled fatty acids back into the reaction vessel.

[0046] As described above, by refluxing at least a portion of the distilled fatty acids back into the reaction vessel, the contamination of the polymer with foreign matter can be further reduced. In contrast, Patent Document 1 states that if the refluxed liquid flows down the inner wall of the reaction vessel, it can cause foreign matter to be present. In the method for producing liquid crystalline resin according to this embodiment, even if the refluxed liquid flows down the inner wall of the reaction vessel, the contamination of the polymer with foreign matter can be further reduced. This is likely because the refluxed liquid can be prevented from causing foreign matter by adjusting both the final polymerization temperature and the temperature of the region in contact with the space above the reaction liquid surface during the melt polycondensation reaction to a predetermined range.

[0047] Figure 1 shows an example of a polymerization apparatus that can be used in the method for producing liquid crystalline resin according to this embodiment. The polymerization apparatus shown in Figure 1 has a reaction vessel 1. The reaction vessel 1 has a stirrer 2, a reflux column 3, a raw material monomer supply port 3, a reduced pressure line and an outlet line 6, and a polymer outlet 7. The reduced pressure line and outlet line 6 may be implemented as one line or as two or more lines. Heating or cooling means 5 are provided on the outer circumference of the reaction vessel 1. In the polymerization apparatus shown in Figure 1, the heating or cooling means 5 is provided separately on the lower outer surface of the reaction vessel 1 (the area from the bottom of the outer surface of the reaction vessel 1 to a point on the outer surface that corresponds to a height roughly equivalent to the reaction liquid level inside the reaction vessel 1) and on the upper outer surface of the reaction vessel 1 (the area on the outer surface that corresponds to the space above the reaction liquid level inside the reaction vessel 1). In one embodiment, the heating or cooling means 5 provided on the lower outer circumferential surface of the reaction vessel 1 may be a heating means (first heating means). In one embodiment, the heating or cooling means 5 provided on the upper outer circumferential surface of the reaction vessel 1 may be a second heating or cooling means. In another embodiment, the heating or cooling means 5 provided on the upper outer circumferential surface of the reaction vessel 1 may be a cooling means.

[0048] The melting point Tm2 of the liquid crystalline resin obtained in the melt polycondensation process is preferably 250 to 370°C, more preferably 275 to 360°C, and even more preferably 330 to 355°C. The method for measuring the melting point Tm2 is as described above.

[0049] The melt viscosity of the liquid crystalline resin obtained in the melt polycondensation process is not particularly limited, and is determined by a cylinder temperature 10 to 30°C higher than the melting point of the liquid crystalline resin and a shear rate of 1000 sec. -1 The melt viscosity measured is preferably 5 Pa·s or more and 150 Pa·s or less, and more preferably 10 Pa·s or more and 100 Pa·s or less.

[0050] The yield of the liquid crystalline resin obtained in the melt polycondensation process relative to the amount of raw material monomer used is preferably 95.0% or higher, more preferably 97.0% or higher, and even more preferably 98.0% or higher.

[0051] (Acylation process) The method for producing liquid crystalline resin may, if necessary, further include a step of acyling the raw material monomers with a fatty acid anhydride before the melt polycondensation reaction.

[0052] As the fatty acid anhydride, known acyling agents can be used, such as acetic anhydride, propionic anhydride, and butyric anhydride. For ease of availability, it is preferable to include acetic anhydride.

[0053] The amount of fatty acid anhydride used is preferably 1.0 to 1.1 equivalents, and more preferably 1.01 to 1.05 equivalents, relative to the total amount of hydroxyl groups in the substances used in the reaction, in terms of ease of reaction control.

[0054] In the acylation step, a catalyst can be used to accelerate the reaction. Examples of catalysts include those described in the section on the melt polycondensation step. The same catalyst used in the melt polycondensation step may be used, or a different catalyst may be used. The amount used can be the same as described above.

[0055] Acylation can be carried out by known methods. For example, a raw material monomer and an acyling agent are mixed and heated in an inert gas environment, preferably under nitrogen gas, at a temperature range of 120 to 160°C for about 0.5 to 5 hours to carry out the acylation reaction and obtain a reaction product containing an acyled product. The acyled product obtained here can be used as a raw material monomer in the melt polycondensation step described above.

[0056] The acylation and polycondensation reactions can be carried out in a single step within one reaction vessel, or they can be carried out using two or more reaction vessels, with the acylation reaction performed in the first step and the polycondensation reaction performed in subsequent steps.

[0057] (Solid phase polymerization process) The method for producing liquid crystalline resin may, if necessary, further include a solid-phase polymerization step after the melt polycondensation reaction step. Solid-phase polymerization can increase the molecular weight of the raw material resin, resulting in a resin with superior strength and heat resistance.

[0058] Solid-phase polymerization can be carried out using conventionally known methods. For example, it can be performed by heating the raw material resin at a temperature 10 to 120°C lower than the liquid crystal formation temperature under reduced pressure or vacuum, in an inert gas stream such as nitrogen gas. The heating method is not particularly limited, and microwave heating, heater heating, etc., can be used. [Examples]

[0059] The present invention will be described in more detail below with reference to examples, but the interpretation of the present invention is not limited by these examples.

[0060] [Example 1] A reaction vessel with a top lid (internal volume 6L), a stirrer, a reflux column, a raw material monomer supply port, a nitrogen inlet, a reduced pressure line, and an outlet line was fitted into the reaction vessel, and the following raw material monomers, a fatty acid metal salt catalyst, and an acylating agent were charged in, and nitrogen purging was started. The reaction vessel has a band heater (first heating means) on the outside of the part of the reaction vessel that is in contact with the reaction liquid to adjust the temperature of the reaction system, and a band heater (second heating means) on the top lid to adjust the temperature of the part of the reaction vessel above the reaction liquid surface. If the temperature of the part of the reaction vessel above the reaction liquid surface is too high, the temperature can be lowered by turning off the band heaters and air cooling. The internal temperature of the reaction vessel was raised to 140°C by a first heating means, and the reaction was carried out at 140°C for 3 hours (acylation step). Subsequently, the internal temperature of the reaction vessel was raised to 340°C over 4.5 hours by the first heating means while adjusting the temperature of the top of the reaction vessel to 320°C using a second heating means. From there, the pressure was reduced to 10 Torr (i.e., 1330 Pa) over 15 minutes, and melt polycondensation was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling-point components (polycondensation reaction step). After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from reduced pressure to atmospheric pressure and then to a pressurized state, and the polymer was discharged from the bottom of the polymerization vessel. The strands were then pelletized to obtain liquid crystalline resin pellets. The shear rate of the obtained pellets was 1000 sec. -1 The measured melt viscosity was 9 Pa·s. (raw materials) 4-Hydroxybenzoic acid (HBA): 1380g (60 mol%) 6-Hydroxy-2-naphthoic acid (HNA): 158g (5 mol%) Terephthalic acid (TA): 485g (17.5 mol%) 4,4'-Dihydroxybiphenyl (BP): 388g (12.5 mol%) N-acetyl-p-aminophenol (APAP): 126g (5 mol%) Metal salt catalyst (potassium acetate catalyst); 110 mg Acylating agent (acetic anhydride); 1665g

[0061] [Example 2] Liquid crystal resin pellets were obtained in the same manner as in Example 1, except that the temperature of the upper part of the reaction vessel was adjusted to 280°C by a second heating means during the polycondensation reaction step. The shear rate of the obtained pellets was 1000 sec. -1 The measured melt viscosity was 10 Pa·s.

[0062] [Comparative Examples 1, 2] Liquid crystal resin pellets were obtained in the same manner as in Example 1, except that the temperature of the upper part of the reaction vessel was adjusted to the temperature shown in Table 1 by a second heating means during the polycondensation reaction step.

[0063] [Example 3] A reaction vessel with a top lid (internal volume 6L), a stirrer, a reflux column, a raw material monomer supply port, a nitrogen inlet, a reduced pressure line, and an outlet line was fitted into the reaction vessel, and the following raw material monomers, a fatty acid metal salt catalyst, and an acylating agent were charged in, and nitrogen purging was started. The reaction vessel has a band heater (first heating means) on the outside of the part of the reaction vessel that is in contact with the reaction liquid to adjust the temperature of the reaction system, and the top lid has a band heater (second heating means) to adjust the temperature of the part of the reaction vessel above the reaction liquid surface. The internal temperature of the reaction vessel was raised to 140°C by a first heating means, and the reaction was carried out at 140°C for 3 hours (acylation step). Subsequently, the internal temperature of the reaction vessel was raised to 360°C over 4.5 hours by the first heating means while adjusting the temperature of the top of the reaction vessel to 320°C using a second heating means. From there, the pressure was reduced to 10 Torr (i.e., 1330 Pa) over 15 minutes, and melt polycondensation was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling-point components (polycondensation reaction step). After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from reduced pressure to atmospheric pressure and then to a pressurized state, and the polymer was discharged from the bottom of the polymerization vessel. The strands were then pelletized to obtain liquid crystalline resin pellets. The shear rate of the obtained pellets was 1000 sec. -1 The measured melt viscosity was 9 Pa·s. (raw materials) 4-Hydroxybenzoic acid (HBA): 37g (2 mol%) 6-Hydroxy-2-naphthoic acid (HNA): 1218g (48 mol%) Terephthalic acid (TA): 560g (25 mol%) 4,4'-Dihydroxybiphenyl (BP): 628g (25 mol%) Metal salt catalyst (potassium acetate catalyst); 330 mg Acylating agent (acetic anhydride); 1418g

[0064] [Example 4] Liquid crystal resin pellets were obtained in the same manner as in Example 1, except that the temperature of the upper part of the reaction vessel was adjusted to 280°C by a second heating means during the polycondensation reaction step. The shear rate of the obtained pellets was 1000 sec. -1 The measured melt viscosity was 8 Pa·s.

[0065] [Comparative Examples 3, 4] Liquid crystal resin pellets were obtained in the same manner as in Example 3, except that the temperature of the upper part of the reaction vessel was adjusted to the temperature shown in Table 1 by a second heating means during the polycondensation reaction step.

[0066] [Example 5] A reaction vessel with a top lid (internal volume 6L), a stirrer, a reflux column, a raw material monomer supply port, a nitrogen inlet, a reduced pressure line, and an outlet line was fitted into the reaction vessel, and the following raw material monomers, a fatty acid metal salt catalyst, and an acylating agent were charged in, and nitrogen purging was started. The reaction vessel has a band heater (first heating means) on the outside of the part of the reaction vessel that is in contact with the reaction liquid to adjust the temperature of the reaction system, and the top lid has a band heater (second heating means) to adjust the temperature of the part of the reaction vessel above the reaction liquid surface. The internal temperature of the reaction vessel was raised to 140°C by a first heating means, and the reaction was carried out at 140°C for 3 hours (acylation step). Subsequently, the internal temperature of the reaction vessel was raised to 360°C over 4.5 hours by the first heating means while adjusting the temperature of the top of the reaction vessel to 320°C using a second heating means. From there, the pressure was reduced to 10 Torr (i.e., 1330 Pa) over 15 minutes, and melt polycondensation was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling-point components (polycondensation reaction step). After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from a reduced pressure state, through an atmospheric pressure state, to a pressurized state, and the polymer was discharged from the lower part of the polymerization vessel. Thereafter, the strands were pelletized to obtain liquid crystalline resin pellets. The melt viscosity of the obtained pellets measured at a shear rate of 1000 sec -1 was 8 Pa·s. (Raw materials) 4-Hydroxybenzoic acid (HBA): 1040 g (48 mol%) 6-Hydroxy-2-naphthoic acid (HNA): 89 g (3 mol%) Terephthalic acid (TA): 548 g (21 mol%) Isophthalic acid (IA): 92 g (3.5 mol%) 4,4'-Dihydroxybiphenyl (BP): 716 g (24.5 mol%) Metal salt catalyst (potassium acetate catalyst); 110 mg Acylating agent (acetic anhydride); 1650 g

[0067] [Example 6] In the polycondensation reaction step, liquid crystalline resin pellets were obtained in the same manner as in Example 1, except that the upper temperature of the reaction vessel was adjusted to 280°C by the second heating means. The melt viscosity of the obtained pellets measured at a shear rate of 1000 sec -1 was 8 Pa·s.

[0068] [Comparative Examples 5, 6] In the polycondensation reaction step, liquid crystalline resin pellets were obtained in the same manner as in Example 5, except that the upper temperature of the reaction vessel was adjusted to the temperature shown in Table 1 by the second heating means.

[0069] [Comparative Example 7] A reaction vessel with a top lid (internal volume 6L), a stirrer, a reflux column, a raw material monomer supply port, a nitrogen inlet, a reduced pressure line, and an outlet line was fitted into the reaction vessel, and the following raw material monomers, a fatty acid metal salt catalyst, and an acylating agent were charged in, and nitrogen purging was started. The reaction vessel has a band heater (first heating means) on the outside of the part of the reaction vessel that is in contact with the reaction liquid to adjust the temperature of the reaction system, and the top lid has a band heater (second heating means) to adjust the temperature of the part of the reaction vessel above the reaction liquid surface. The internal temperature of the reaction vessel was raised to 140°C by a first heating means, and the reaction was carried out at 140°C for 3 hours (acylation step). Subsequently, the internal temperature of the reaction vessel was raised to 320°C over 4.5 hours by the first heating means while adjusting the temperature of the top of the reaction vessel to 195°C using a second heating means. From there, the pressure was reduced to 10 Torr (i.e., 1330 Pa) over 15 minutes, and melt polycondensation was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling-point components (polycondensation reaction step). After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from reduced to atmospheric pressure and then to a pressurized state, and the polymer was discharged from the bottom of the polymerization vessel. Subsequently, the strands were pelletized to obtain liquid crystalline resin pellets. (raw materials) 4-Hydroxybenzoic acid (HBA): 1697g (67 mol%) Terephthalic acid (TA): 518g (17 mol%) 4,4'-Dihydroxybiphenyl (BP): 205 g (6 mol%) Ethylene glycol (EG): 114g (10 mol%) Metal salt catalyst (potassium acetate catalyst); 110 mg Acylating agent (acetic anhydride); 1910g

[0070] [Measurement and Evaluation] (yield) The yield relative to the amount of raw material monomer used was calculated from the amount of liquid crystalline resin pellets obtained. A yield of 98.0% or higher was rated as "3", a yield of 95.0% or higher but less than 98.0% was rated as "2", and a yield of less than 95.0% was rated as "1", with a yield of 2 or higher being considered acceptable. The results are shown in Table 1.

[0071] (Melting point Tm2) Using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Corporation), the obtained liquid crystalline resin pellets were heated from room temperature at a heating rate of 20°C / min. The endothermic peak temperature (Tm1) was measured, the pellets were held at (Tm1+40)°C for 2 minutes, cooled to room temperature at a cooling rate of 20°C / min, and then heated again at a heating rate of 20°C / min. The endothermic peak temperature (Tm2) observed at this time was measured as the melting point. Using the obtained melting point Tm2 values, the values ​​of [(final polymerization temperature) - (melting point Tm2)] and [(temperature at the top of the polymerization vessel) - (melting point Tm2)] were calculated. The results are shown in Table 1.

[0072] (Foreign object) Liquid crystal resin was formed into films (0.5g / sheet, 100μm thickness) using a high-temperature hot press machine (NP-SNH, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The films were illuminated with a white backlight, and the number of foreign objects larger than 0.3mm was checked using a magnifying glass. This check was performed on five films (2.5g), and the number of foreign objects per unit weight was calculated. A count of 0 foreign objects / g was indicated as "good," and a count of 1 or more foreign objects / g was indicated as "poor."

[0073] [Table 1]

[0074] As shown in Table 1, in the methods of Examples 1 to 6, the final polymerization temperature was between the melting point Tm2°C and (Tm2+30)°C, and the temperature of the top (lid) of the reaction vessel was adjusted to between (Tm2-100)°C and (Tm2-5)°C. The yield of the liquid crystalline resin obtained by these methods was 95.0% or higher (i.e., rating 2 or higher), demonstrating that liquid crystalline resin could be produced with high yield. Furthermore, no foreign matter was found in the molded products formed from the liquid crystalline resin films. In contrast, in the methods of Comparative Examples 1, 3, and 5, although the final polymerization temperature was within the specified range, foreign matter was found in the molded product formed from the liquid crystalline resin film because the temperature at the top of the reaction vessel was too high. In the methods of Comparative Examples 2, 4, 6, and 7, although the final polymerization temperature was within the specified range, the yield of the obtained liquid crystalline resin was low, less than 95%, because the temperature at the top of the reaction vessel was too low. [Industrial applicability]

[0075] The method for producing liquid crystalline resin according to this embodiment can suppress the inclusion of foreign matter and produce liquid crystalline resin in high yield, thus enabling the production of high-quality liquid crystalline resin in high yield and possessing industrial applicability. [Explanation of Symbols]

[0076] 1. Reaction vessel 2. Agitator 3 reflux column 4. Raw material monomer supply port 5. Heating or cooling means 6. Depressurization lines and outflow lines 7 Polymer outlet

Claims

1. A method for manufacturing liquid crystalline resin, The process involves melt polycondensation of a starting monomer containing one or more selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof in a reaction vessel. When a melt polycondensation reaction is performed, and the melting point of the liquid crystalline resin is Tm2, A method for producing a liquid crystalline resin, comprising: melting and polycondensing raw material monomers at a final polymerization temperature within the range of Tm2 to (Tm2 + 30)°C; and maintaining the temperature of the region of the reaction vessel, including the sides and top surface of the reaction vessel that are in contact with the space above the reaction liquid surface during the melting and polycondensing reaction, within the range of (Tm2 - 40) to (Tm2 - 5)°C.

2. The raw material monomers are One or more selected from the group consisting of aromatic or alicyclic dicarboxylic acids and their polymerizable derivatives, One or more selected from the group consisting of aromatic or alicyclic diols, aromatic or alicyclic hydroxyamines, aromatic or alicyclic diamines, and polymerizable derivatives thereof, A method for producing a liquid crystal resin according to claim 1, further comprising:

3. A method for producing a liquid crystalline resin according to claim 1 or 2, further comprising acyling the raw material monomer with a fatty acid anhydride before carrying out a melt polycondensation reaction.

4. A method for producing a liquid crystalline resin according to claim 1 or 2, wherein the reaction vessel includes a stirrer, a reflux column, a raw material monomer supply port, a reduced pressure line, and an outlet line.

5. The melt polycondensation reaction includes carrying out the melt polycondensation reaction while removing fatty acids by distillation. A method for producing a liquid crystalline resin according to claim 1 or 2, wherein at least a portion of the distilled fatty acids is refluxed into a polymerization vessel.

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